YbgC

YbgCis believed to have first appeared in the Tol complex with the separation of the δε proteobacteria from the αβγ proteobacteria.

Structure
YbgC is a cytoplasmic protein in the Tol-Pal complex. In Helicobacter pylori, the protein is part of a 'hot-dog' family of proteins, with an epsilongamma tetrameric arrangement.

Function
The protein displays thioesterase activity towards acyl-CoA thioesters, and has a strong sequence conservation with its active site residues with other proteins of a similar function for example with the Pseudonomas sp. strain CBS3 4-hydroxybenzoyl-CoA thioesterase.

However, its role within the Tol complex itself remains unknown, although it may be involved in the acetylation of another protein within the complex, with the role of an activity-regulator. It is also thought to be involved in the cell division complex of Tol-Pal.